 /*******************************************************************************
  * Copyright (c) 2004, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.intro.impl.model.loader;

 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.Platform;
 import org.eclipse.ui.internal.intro.impl.model.AbstractBaseIntroElement;
 import org.eclipse.ui.internal.intro.impl.model.AbstractIntroElement;
 import org.eclipse.ui.internal.intro.impl.model.AbstractIntroIdElement;
 import org.eclipse.ui.internal.intro.impl.model.util.BundleUtil;
 import org.eclipse.ui.internal.intro.impl.util.Log;
 import org.osgi.framework.Bundle;
 import org.w3c.dom.Element ;


 /**
  * Utilities class for help with loading the intro model from the Platform
  * runtime model and from the DOM of content files.
  */
 public class ModelLoaderUtil {

     /**
      * Utility method to validate an elements name.
      *
      * @param element
      * @param validName
      * @return
      */
     public static boolean isValidElementName(IConfigurationElement element,
             String validName) {

         if (element.getName().equals(validName))
             return true;
         // bad element name.
 return false;
     }

     /**
      * Utility method to verify that there is only a single configElement in the
      * passed array of elements. If the array is empty, null is returned. If
      * there is more than one element in the array, the first one is picked, but
      * this fact is logged. Attribute passed is used for logging.
      *
      * @param configElements
      * @return the first configElement in the array, or null if the array is
      * empty.
      */
     public static IConfigurationElement validateSingleContribution(
             IConfigurationElement[] configElements, String logAttribute) {

         int arraySize = configElements.length;
         if (arraySize == 0)
             // No one contributed to extension. return null.
 return null;

         // we should only have one, so use first one.
 IConfigurationElement configElement = configElements[0];
         if (Log.logInfo) {
             String msg = "Loading " + getLogString(configElement, logAttribute); //$NON-NLS-1$
 Log.info(msg);
         }

         if (arraySize != 1) {
             // we have more than one, warn in the log.
 for (int i = 1; i < arraySize; i++)
                 // log each extra extension.
 Log.warning(getLogString(configElements[i], logAttribute)
                         + " ignored due to multiple contributions"); //$NON-NLS-1$
 }
         return configElement;
     }

     /**
      * Utility method to return a string to display in .log. If logAttribute is
      * not null, its value is also printed.
      */
     public static String getLogString(IConfigurationElement element,
             String logAttribute) {
         StringBuffer buffer = new StringBuffer (element.getName());
         buffer.append(" element"); //$NON-NLS-1$
 if (logAttribute != null) {
             buffer.append(" with "); //$NON-NLS-1$
 buffer.append(logAttribute);
             buffer.append("=\""); //$NON-NLS-1$
 buffer.append(element.getAttribute(logAttribute));
         }
         buffer.append("\" in extension: "); //$NON-NLS-1$
 buffer.append(element.getDeclaringExtension()
             .getExtensionPointUniqueIdentifier());
         buffer.append(" in Bundle: "); //$NON-NLS-1$
 buffer.append(element.getContributor().getName());


         return buffer.toString();
     }




     /**
      * Utility method to verify that there is only a single Element in the
      * passed array of elements. If the list is empty, null is returned. If
      * there is more than one element in the array, the first one is picked, but
      * this fact is logged. Attribute and bundle passed is used for logging.
      *
      * @param Elements
      *
      * @return the first Element in the array, or null if the array is empty.
      */
     public static Element validateSingleContribution(Bundle bundle,
             Element[] elements, String logAttribute) {

         int arraySize = elements.length;
         if (arraySize == 0)
             // element list in empty. return null.
 return null;

         // we should only have one, so use first one.
 Element element = elements[0];
         if (Log.logInfo) {
             String msg = "Loading " //$NON-NLS-1$
 + getLogString(bundle, element, logAttribute);
             Log.info(msg);
         }

         if (arraySize != 1) {
             // we have more than one, warn in the log.
 for (int i = 1; i < arraySize; i++) {
                 if (Log.logWarning)
                     // log each extra extension.
 Log.warning(getLogString(bundle, element, logAttribute)
                             + " ignored due to multiple contributions"); //$NON-NLS-1$
 }
         }
         return element;
     }

     /**
      * Utility method to return a string to display in .log. If logAttribute is
      * not null, its value is also printed.
      */
     public static String getLogString(Bundle bundle, Element element,
             String logAttribute) {
         StringBuffer buffer = new StringBuffer (element.getNodeName());
         buffer.append(" element"); //$NON-NLS-1$
 if (logAttribute != null) {
             buffer.append(" with "); //$NON-NLS-1$
 buffer.append(logAttribute);
             buffer.append("=\""); //$NON-NLS-1$
 buffer.append(element.getAttribute(logAttribute));
         }
         buffer.append("\" from xml file in Bundle:"); //$NON-NLS-1$
 buffer.append(bundle.getSymbolicName());


         return buffer.toString();
     }



     /**
      * Util class for creating class instances from plugins.
      *
      * @param pluginId
      * @param className
      * @return
      */
     public static Object createClassInstance(String pluginId, String className) {
         // quick exits.
 if (pluginId == null || className == null)
             return null;
         Bundle bundle = Platform.getBundle(pluginId);
         if (!BundleUtil.bundleHasValidState(bundle))
             return null;

         Class aClass;
         Object aObject;
         try {
             aClass = bundle.loadClass(className);
             aObject = aClass.newInstance();
             return aObject;
         } catch (Exception e) {
             Log.error("Intro Could not instantiate: " + className + " in " //$NON-NLS-1$ //$NON-NLS-2$
 + pluginId, e);
             return null;
         }
     }



     /**
      * Creates a key for the given element. Returns null if any id is null along
      * the path.
      *
      * @param element
      * @return
      */
     public static StringBuffer createPathToElementKey(
             AbstractIntroIdElement element, boolean full) {
         if (element.getId() == null)
             return null;
         StringBuffer buffer = new StringBuffer (element.getId());
         AbstractBaseIntroElement parent = (AbstractBaseIntroElement) element
             .getParent();
         while (parent != null
                 && !parent.isOfType(AbstractIntroElement.MODEL_ROOT)) {
             if (parent.getId() == null)
                 return null;
             buffer.insert(0, parent.getId() + "."); //$NON-NLS-1$
 parent = (AbstractBaseIntroElement) parent.getParent();
         }
         return buffer;
     }
 }

